1 package sa1004
2 3 import (
4 "fmt"
5 "go/ast"
6 "go/constant"
7 "go/types"
8 9 "honnef.co/go/tools/analysis/code"
10 "honnef.co/go/tools/analysis/edit"
11 "honnef.co/go/tools/analysis/lint"
12 "honnef.co/go/tools/analysis/report"
13 "honnef.co/go/tools/pattern"
14 15 "golang.org/x/tools/go/analysis"
16 "golang.org/x/tools/go/analysis/passes/inspect"
17 )
18 19 var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
20 Analyzer: &analysis.Analyzer{
21 Name: "SA1004",
22 Run: run,
23 Requires: []*analysis.Analyzer{inspect.Analyzer},
24 },
25 Doc: &lint.RawDocumentation{
26 Title: `Suspiciously small untyped constant in \'time.Sleep\'`,
27 Text: `The \'time\'.Sleep function takes a \'time.Duration\' as its only argument.
28 Durations are expressed in nanoseconds. Thus, calling \'time.Sleep(1)\'
29 will sleep for 1 nanosecond. This is a common source of bugs, as sleep
30 functions in other languages often accept seconds or milliseconds.
31 32 The \'time\' package provides constants such as \'time.Second\' to express
33 large durations. These can be combined with arithmetic to express
34 arbitrary durations, for example \'5 * time.Second\' for 5 seconds.
35 36 If you truly meant to sleep for a tiny amount of time, use
37 \'n * time.Nanosecond\' to signal to Staticcheck that you did mean to sleep
38 for some amount of nanoseconds.`,
39 Since: "2017.1",
40 Severity: lint.SeverityWarning,
41 MergeIf: lint.MergeIfAny,
42 },
43 })
44 45 var Analyzer = SCAnalyzer.Analyzer
46 47 var (
48 checkTimeSleepConstantPatternQ = pattern.MustParse(`(CallExpr (Symbol "time.Sleep") lit@(IntegerLiteral value))`)
49 checkTimeSleepConstantPatternRns = pattern.MustParse(`(BinaryExpr duration "*" (SelectorExpr (Ident "time") (Ident "Nanosecond")))`)
50 checkTimeSleepConstantPatternRs = pattern.MustParse(`(BinaryExpr duration "*" (SelectorExpr (Ident "time") (Ident "Second")))`)
51 )
52 53 func run(pass *analysis.Pass) (interface{}, error) {
54 fn := func(node ast.Node) {
55 m, ok := code.Match(pass, checkTimeSleepConstantPatternQ, node)
56 if !ok {
57 return
58 }
59 n, ok := constant.Int64Val(m.State["value"].(types.TypeAndValue).Value)
60 if !ok {
61 return
62 }
63 if n == 0 || n > 120 {
64 // time.Sleep(0) is a seldom used pattern in concurrency
65 // tests. >120 might be intentional. 120 was chosen
66 // because the user could've meant 2 minutes.
67 return
68 }
69 70 lit := m.State["lit"].(ast.Node)
71 report.Report(pass, lit,
72 fmt.Sprintf("sleeping for %d nanoseconds is probably a bug; be explicit if it isn't", n), report.Fixes(
73 edit.Fix("explicitly use nanoseconds", edit.ReplaceWithPattern(pass.Fset, lit, checkTimeSleepConstantPatternRns, pattern.State{"duration": lit})),
74 edit.Fix("use seconds", edit.ReplaceWithPattern(pass.Fset, lit, checkTimeSleepConstantPatternRs, pattern.State{"duration": lit}))))
75 }
76 code.Preorder(pass, fn, (*ast.CallExpr)(nil))
77 return nil, nil
78 }
79